Effect of microparticulation and xanthan gum on the stability and lipid digestion of oil-in-water emulsions stabilized by whey protein†
Since lipid digestion is an interfacial process, food emulsions are increasingly being seen as a mechanism for controlling lipid uptake. Oil-in-water emulsions stabilized by whey protein (WP) and protein-xanthan gum (XG) mixtures were designed to investigate the influence of interfacial structures on lipid digestion using an in vitro digestion model. The interfacial layers with different structures were designed using microparticulated whey protein (MWP) and MWP-XG mixtures. The increase in the volume average diameter of proteins indicated that the WPs aggregated to form micro-particles during microparticulation. The increase in the protein surface hydrophobicity index and the measurement results from the Magnetic Resonance Imaging System indicated that the protein hydrophilic groups were embedded and that the protein hydrophobic groups were exposed. Under in vitro conditions, the emulsions stabilized by microparticulated whey proteins and protein-XG mixtures were more stable than the WP emulsions, and the microparticulated whey proteins and protein-XG mixtures were more effective for decreasing the digestion rate, as shown by the stability analysis and free fatty acid release rates. These results help elucidate the influence of the interfacial structure on lipid digestion. The control of lipid digestibility within the gastrointestinal tract might be important for the design and development of reduced-fat foods and novel functional foods for controlling bioactive release.